https://developer.salesforce.com/trailhead/en/project/quickstart-apex/quickstart-apex-2
In working on this project in trailhead I'm receiving the error on Line 1 that it sees a problem as unexpected token:'void'
This one should be easy since it's just copying code.

Is anyone else having difficulty?

I am getting an error on my challenge for the Advanced Admin for creating the formula for days since last account was updated and it continues to tell me that it does not exist. I have the field and it is functioning correctly with activity placed within the account.  Is there a reason that the Trailhead would not recognize my field and formula?

I am getting an error on my challenge for the Advanced Admin for creating the formula for days since last account was updated and it continues to tell me that it does not exist. I have the field and it is functioning correctly with activity placed within the account.  Is there a reason that the Trailhead would not recognize my field and formula?

Trailhead Module 3:  Create a formula field that determines the number of days between today and the last activity date for a case's account.
Your support team has asked for improved visibility on account activity level at the time they’re helping with customer issues. Specifically, when they’re looking at a case, they’d like to see an at-a-glance view of the number of days since the case’s related account was last active. Create the formula using these requirements.The formula should be on the Case object.
The formula should be of return type Number.
The formula should be named 'Days Since Last Update' and have a resulting API Name of 'Days_Since_Last_Update__c'.
The formula should return the number of days between the account’s Last Activity Date and today.

I created the following:

I created a new custom formula field with return type number and called Days Since Last Update.
I created this formula: Account.LastActivityDate - TODAY()

I get this error message:

Challenge not yet complete... here's what's wrong: 
The 'Days_Since_Last_Update__c' formula field did not return the correct number of days between an Account’s Last Activity Date and today

Can you please assist what I did wrong?  I'm not sure if my formula is even correct with the challenge.  Please help!

Thank you.